text: A restriction digest is a procedure used in molecular biology to prepare DNA for analysis or other processing.  It is sometimes termed DNA fragmentation, though this term is used for other procedures as well. In a restriction digest, DNA molecules are cleaved at specific restriction sites of 4-12 nucleotides in length by use of restriction enzymes which recognize these sequences. 
  The resulting digested DNA is very often selectively amplified using polymerase chain reaction (PCR), making it more suitable for analytical techniques such as agarose gel electrophoresis, and chromatography.  It is used in genetic fingerprinting, plasmid subcloning, and RFLP analysis.